1. Field of the Invention
The present invention relates to mobile radio communication, and more particularly to a parallel distributed sample acquisition (PDSA) system for a mobile radio communication system.
2. Background of the Related Art
The distributed sample acquisition (DSA) technique, recently presented for fast acquisition of long-period PN sequences, substantially outperforms the existing serial search acquisition (SSA) techniques, in DS/CDMA system-based mobile radio communication systems. The DSA technique exhibited more than 100 times faster acquisition for the longer period PN sequences when applied to the IS-95 specification. Thus, since the period of the PN sequences is long, the acquisition time performance can be reduced over that of the SSA technique.
Features of the DSA technique are given as follows. First, a transmitter takes state samples for a main sequence from a main shift register generator (SRG) one by one to map the samples to binary state symbols. It then spreads it to a short-period igniter sequence, thereby outputting it as a state signal through the pilot channel. In this case, the example of the transmitter is a base station.
A receiver acquires the igniter sequence of the received state signal to despread the pilot channel to successively detect the state samples of the main sequence one by one to correct the receiver main SRG state. This enables synchronizing the main SRG of the receiver to the transmitter main SRG. The example of the receiver is a mobile station.
The DSA technique can obtain a fast synchronization time between the transmitter and the receiver, but can be employed only for the binary signaling systems which transmit one bit per data symbol. Therefore, it has limited usefulness and fails to ensure an optimal transmission ratio due to the channel environment.
In practice, however, there are many DS/CDMA systems that adopt non-binary signaling, such as quaternary or 64-ary signaling for data transmission. Such systems have been commercialized and are widely used in communication systems. These DS/CDMA systems adopt a 2b-ary (b greater than 1) method where at least one or more multi-bits correspond to one transmission symbol, in order to convey data in the unit of bit through binary transmission symbols and to increase the signal transmission ratio.
For this reason, when the proposed DSA technique is used in DS/CDMA systems, the DSA requires another dedicated modulator and demodulator set to convey the binary state signal for the synchronization of the SRG. But this arrangement makes the system inefficient. Even if dedicated MODEM equipment is employed for the state signal conveyance, the type of optimal signaling for fast acquisition may not necessarily be binary due to the allocated power budget, the igniter sequence period, and the channel environment.
Therefore, a more generalized DSA scheme is needed that can handle the SRG synchronization process for bit single schemes as well as multi-bit schemes, which ensures an optimal conveyance ratio under the conveyance environment, and achieves faster synchronization between the transmitter and the receiver. In this case, upon the transmission of the multi-bit of one bit or more, in the channel environment where the transmission error ratio is considerably low the multi-bit transmission can ensure the faster synchronization between the transmitter and the receiver.
The above references are incorporated by reference herein where appropriate for appropriate teachings of additional or alternative details, features and/or technical background.
An object of the invention is to provide a PDSA system that substantially obviates the problems caused by the limitations of the related art.
Another object of the invention is to provide a PDSA system that can effectively handle an SRG synchronization process in non-binary DS/CDMA systems and a signal acquisition method using the same.
Another object of the present invention is to extend the DSA technique to a PDSA technique for the SRG synchronization or the state signal processes of the SRGs of the transmitter and the receiver for a multi-bit state symbol.
It is another object of the invention to provide a PDSA system which adopts a PDSA scheme for fast synchronization of a spread band signal and a signal acquisition method using the PDSA system.
To achieve at least these objects in whole or in parts, there is provided a parallel distributed sample acquisition system including a transmitter for taking at least one or more first state samples at the same time from a first main sequence for data spreading and spreading the first state sample to an M-ary symbol state signal, thereby transmitting the state signal; and a receiver for detecting the first state sample from the transmitted state signal, comparing the first state sample detected with a second state sample taken from a second main sequence for data despreading, and correcting the state of the second main sequence in accordance with the compared result, thereby enabling the synchronization of the second main sequence to the first main sequence.
To achieve at least these objects in whole or in parts, there is further provided a parallel distributed sample acquisition system including a transmitter for taking a plurality of first state samples corresponding to user data from a main sequence for data spreading to spread the first state samples to a plurality of binary symbols state signals and spreading a plurality of user data, using the main sequence, thereby transmitting the plurality of state signals; and a receiver for despreading the plurality of state signals transmitted from the transmitter, detecting each first state sample from each state signal, comparing the plurality of first state samples detected with a plurality of second state samples taken from a second igniter sequence, and correcting the state of a second igniter sequence in accordance with the compared result, thereby despreading the data outputted from the transmitter.
To achieve at least these objects in whole or in parts, there is further provided a signal acquisition method using a parallel distributed sample acquisition system, including taking at least one or more state samples from a first main sequence for data spreading at the same time every state symbol period in a transmitter; mapping each state sample to a 2b-ary state symbol; spreading the mapped state symbol to an igniter sequence to transmit the spread symbol as a state signal of the first main sequence; synchronizing the igniter sequence with the transmitted state signal in a receiver; depsreading the transmitted state signal to detect the transmitted state sample from every state symbol; comparing the detected state sample with each state sample taken from a second main sequence for data dispreading; and correcting the state of the second main sequence for the synchronization of the second main sequence to the first main sequence.
To achieve at least these objects in whole or in parts, there is further provided a signal acquisition method using a parallel distributed sample acquisition system, including taking a plurality of state samples from a first main sequence for data spreading in a transmitter; parallel-spreading the each state symbol to a plurality of binary symbols by using igniter sequence to transmit the spread symbol as a state signal of the first main sequence; synchronizing the igniter sequence with the transmitted state signal in a receiver; despreading the transmitted state signal to detect each state sample of the first main sequence; comparing the detected state sample with each state sample taken from a second main sequence for data despreading; and correcting the state of the second main sequence for the synchronization of the second main sequence to the first main sequence.
Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objects and advantages of the invention may be realized and attained as particularly pointed out in the appended claims.